code: def test_single_process(idtype):
      hg = create_test_graph(idtype=idtype)
      hg_share = hg.shared_memory("hg")
      hg_rebuild = dgl.hetero_from_shared_memory("hg")
      hg_save_again = hg_rebuild.shared_memory("hg")
      _assert_is_identical_hetero(hg, hg_share)
      _assert_is_identical_hetero(hg, hg_rebuild)
      _assert_is_identical_hetero(hg, hg_save_again)
  
file_path: dgl/tests/python/common/test_heterograph-shared-memory.py
imports: import io
  import multiprocessing
  import os
  import pickle
  import unittest
  import backend
  import dgl
  import dgl.function
  import networkx
  import scipy.sparse
  from dgl.graph_index import create_graph_index
  from dgl.utils import toindex
  from utils import parametrize_idtype
label_desc: Use image node_id 3 for calling a global function with example usage: test_single_process(idtype) without return types